I've never had morels (and for obvious reasons refuse to try) but the reaction is more or less severe depending on the mushroom. Whitecaps tend to make me sweaty and nauseous, portobellos make me wheezy and forcefully vomiting. Shiitake mushrooms will send me to the hospital. It's such an agitating allergy to have, because you never know when there's mushrooms in a sauce or something like that, and you'll end up sick.